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- Intrapopulation differences in biological traits and impacts in a highly invasive freshwater speciesPublication . Alves, Henrique; Gonçalves, Diana; Nogueira, António Barbosa; Teixeira, Amilcar; Padilha, Janeide; Sousa, RonaldoIndividual variation assessments are essential to better understand population and community dynamics, as well ecosystem functioning. Although researchers have long recognized this aspect, only recently has evidence accumulated about the ecological importance of variation within species. The incorporation of individual variation provides an even more complete description of the effects a species may have on ecosystems and this detailed ecological knowledge can be especially important in the context of biological invasions. In this study, we used an invasion gradient of the signal crayfish Pacifastacus leniusculus in the Rabaçal River (NE Portugal) to assess possible intrapopulation differences in key biological traits and evaluate possible changes in ecological impacts. For this, we collected individuals from the core and front of an invasion gradient to characterize several traits such as abundance, size, sex-ratio, body condition, behaviour (i.e. boldness), and trophic niche. In addition, we performed two laboratory experiments to assess possible differences regarding the consumption of prey (gastropods), leaf mass loss, and nutrients release. Signal crayfish from the front of the invasion gradient have lower abundance, are larger, predominantly male, have better body condition in both sexes, exhibit increased boldness, and have higher δ 15 N and lower δ 13 C values. In addition, in experimental conditions, signal crayfish from the front of the invasion gradient consumed more gastropods and leaves and increased the concentration of nitrates and phosphates in the water. Overall, the signal crayfish has different biological traits and distinct ecological impacts along the invasion gradient in the studied river. Our study demonstrates the relevance of assessing biological traits and impacts of invasive species at the intrapopulation level.
- Methyl-end desaturases determine the capability for de novo biosynthesis of polyunsaturated fatty acids in bivalvesPublication . Kabeya, Naoki; Ramos-Llorens, Marc; Nakano, Yo; Gomes-dos-Santos, André; Teixeira, Amilcar; Fujibayashi, Megumu; Haro, Juan G.; Navarro, Juan C.; Castro, L. Filipe C.; Haga, Yutaka; Monroig, ÓscarRecent studies have shown that many invertebrate species possess methyl-end desaturases (herein referred to as ‘ωx’), enabling biosynthesis of polyunsaturated fatty acids (PUFA). However, the phylogenetic distribution of these enzymes across the animal kingdom remains puzzling, possibly due to horizontal gene transfer (HGT) and/ or independent large-scale gene loss in certain invertebrate lineages. In molluscs, ωx genes have been identified in various cephalopods and gastropods but remain barely explored in bivalves. The increasing availability of genomic and transcriptomic resources enables a comprehensive exploration of the ωx gene repertoire in bivalves. To elucidate the distribution of ωx in bivalves, we conducted a broad homology search across existing genome and transcriptome assemblies, followed by functional characterisation of ωx in lineage representative species. Our results revealed no ωx-like sequences in any of the 65 Pteriomorphia species, suggesting gene loss in this clade. However, ωx-like sequences were found in Protobranchia, Palaeoheterodonta and Imparidentia. We analysed ωx from Solemya pusilla (Protobranchia), Lanceolaria oxyrhyncha and Margaritifera margaritifera (Palaeoheterodonta), and Ruditapes philippinarum and Tridacna crocea (Imparidentia). Except for M. margaritifera, which had two ωx genes, each species had a single ωx gene. Functional analysis showed Δ15Δ17Δ19 desaturase activity in the R. philippinarum and T. crocea ωx, while the L. oxyrhyncha ωx exhibited Δ15Δ17 activity but not Δ19. Both ωx from M. margaritifera showed no detectable activity in yeast. Interestingly, the S. pusilla ωx exhibited Δ12 desaturase activity. These findings highlight the diversity of ωx desaturation capabilities in bi- valves, with significant gene loss in Pteriomorphia
- Subtle ecological effects of the invasive signal crayfish (Pacifastacus leniusculus) on Iberian fish communitiesPublication . Oliveira, Bruno; Nogueira, António B.; Teixeira, Amilcar; Sousa, RonaldoThe introduction of non-native species can disrupt the structure of communities and affect the functioning of freshwater ecosystems, disturbing various taxonomic groups, including fish. This study aimed to assess the ecological effects of the recent introduction of the signal crayfish Pacifastacus leniusculus in the fish communities in the Rabaçal and Tuela River basins (Montesinho Natural Park and adjacent areas; NE of Portugal), an area with very low human disturbance. A total of 34 sites (18 invaded and 16 non-invaded) were sampled in the summer of 2022 and comparisons were made between invaded and non-invaded sites concerning abundance, biomass, richness and diversity of fish communities. In addition, we compared the physiological condition of the sampled species. A total of 2307 fishes belonging to six different species were collected and results indicated almost no negative (except diversity) effects at the community level. However, species-specific analysis revealed a decrease in the abundance of the Iberian chub Squalius carolitertii in invaded sites. We also observed a lower physiological condition of the brown trout Salmo trutta. Although the ecological effects appear to be subtle, ongoing monitoring of signal crayfish populations and their effects on fish communities is essential, using this study as a baseline for future comparisons. Additionally, urgent management measures—such as controlling and containing signal crayfish populations and raising local awareness—should be considered, given the conservation significance of the study area and the potential negative ecological effects of this non-native species.
- Epidemiology of the microsporidium nosema ceranae in four mediterranean countriesPublication . Jabal-Uriel, Clara; Barrios, Laura; Bonjour-Dalmon, Anne; Caspi-Yona, Shiran; Chejanovsky, Nor; Erez, Tal; Henriques, Dora; Higes, Mariano; Le Conte, Yves; Lopes, Ana; Meana, Aranzazu; Alice Pinto, M.; Teixeira, Amílcar; Reyes-Carreño, Maritza; Soroker, Victoria; Martín-Hernández, RaquelNosema ceranae is a highly prevalent intracellular parasite of honey bees’ midgut worldwide. This Microsporidium was monitored during a long-term study to evaluate the infection at apiary and intra-colony levels in six apiaries in four Mediterranean countries (France, Israel, Portugal, and Spain). Parameters on colony strength, honey production, beekeeping management, and climate were also recorded. Except for São Miguel (Azores, Portugal), all apiaries were positive for N. ceranae, with the lowest prevalence in mainland France and the highest intra-colony infection in Israel. A negative correlation between intra-colony infection and colony strength was observed in Spain and mainland Portugal. In these two apiaries, the queen replacement also influenced the infection levels. The highest colony losses occurred in mainland France and Spain, although they did not correlate with the Nosema infection levels, as parasitism was low in France and high in Spain. These results suggest that both the effects and the level of N. ceranae infection depends on location and beekeeping conditions. Further studies on host-parasite coevolution, and perhaps the interactions with other pathogens and the role of honey bee genetics, could assist in understanding the difference between nosemosis disease and infection, to develop appropriate strategies for its control.
- Interspecific differences in the physiological condition of native freshwater mussels in response to the invasive Asian clam Corbicula flumineaPublication . Modesto, Vanessa; Ilarri, Martina; Castro, Paulo S.; Carvalho, Francisco; Cavalheri, Thais; Lopes-Lima, Manuel; Teixeira, Amílcar; Ozório, Rodrigo O.A.; Antunes, Carlos; Sousa, RonaldoThe Asian clam Corbicula fluminea has been widely introduced into aquatic ecosystems and may impact the physiological condition and survival of native freshwater mussels. However, very few studies have evaluated this issue quantitatively. To fill this gap, manipulative field experiments were performed to assess two possible mechanisms of impact on native mussels: (i) interspecific interactions, and (ii) C. fluminea die-offs. We assessed these effects by measuring the physiological condition through the analysis of glycogen content in the foot tissue of the native freshwater mussel species Anodonta anatina, Potomida littoralis, and Unio delphinus. Although with interspecific differences, our results suggest that C. fluminea can impact the physiological condition of native freshwater mussels. Anodonta anatina showed positive significant variations on glycogen content when subjected to high densities of live C. fluminea in contrast to the other native species studied, P. littoralis and U. delphinus, where no significances were observed. On the other hand, these native species do not seem be significantly impacted by the decomposition of C. fluminea resulting from a die-off. Overall, and contrary to our expectations, both experiments showed a positive (or no) effect of C. fluminea on the physiological condition of the three freshwater mussel species.
- Invasive dynamics of the signal crayfish Pacifastacus leniusculus in a protected areaPublication . Carvalho, Francisco; Alves, Henrique; Pascoal, Cláudia; Castro, Paulo; Miranda, Fernando Jorge Veloso; Teixeira, Amílcar; Cássio, Fernanda; Sousa, RonaldoInvasive species have been drivers of biodiversity loss and functional changes in aquatic ecosystems, including in protected areas. Therefore, monitoring population invasion dynamics and biological traits is fundamental to better understand their ecological and economic impacts and for management actions development. We followed signal crayfish (Pacifastacus leniusculus) invasion in Rabaçal River upper reach at Montesinho Natural Park, Portugal. We collected information on the spread and biological traits (abundance, size, weight, physical condition, sex ratio, and aggressiveness) to assess differences between invasion core and front areas and among years. Signal crayfish population remained restricted since first reports in 2013 in the invasion core until 2017. After 2019, signal crayfish population has been spreading downstream, decreasing abundance at invasion core but increasing at invasion front. Significant higher number of crayfish with claw loss indicate potential higher signs of aggressiveness in the invasion front. Results also demonstrate a significant dominance of females although sex ratio is closer to 1:1 at the invasion front. Overall, results indicate signal crayfish is spreading and increasing their abundance at Rabaçal River highlighting the need for immediate management actions to hold dispersion and mitigate possible impacts.
- E-Learning from nature: picking from nature the inspiration to teach and learn sciencePublication . Pereira, Ana I.; Ferreira, Olga; Barreiro, M.F.; Teixeira, Amílcar; Cortez, José Paulo; Aguiar, CarlosThis work aims to present the work done so far by he Polytechnic Institute of Bragança (IPB) within the projet E-learning form nature.
- Avaliação da performance de stocks de truta-fário selvagem e de cativeiroPublication . Hungulo, Sílvia Laurinda Rafael; Teixeira, Amílcar; Geraldes, Ana MariaA truta-fário (Salmo trutta) é uma espécie autóctone das águas interiores portuguesas, sendo importante do ponto de vista económico e da pesca desportiva. O presente estudo tem como objetivo avaliar a “performance” de indivíduos selvagens e de indivíduos criados em cativeiro e, assim, obter dados que possam auxiliar os aquicultores a tomarem as melhores decisões para a produção desta espécie. As experiências decorreram durante dois meses: de Agosto a Outubro de 2016 no Posto Aquícola de Castrelos. Durante este período, os peixes selvagens e de cativeiro foram mantidos em dois tanques separados e alimentados, com uma periodicidade bissemanal, com uma dieta mista composta por farinha de peixe e por macroinvertebrados capturados no rio Baceiro. No que respeita à relação comprimento-peso de ambos os stocks foi observado um crescimento alométrico negativo (b <3), ou seja, os peixes crescem mais em comprimento do que em biomassa. Mas, dois meses após a realização das experiências, verificou-se uma evolução na tendência anteriormente observada, com um crescimento mais isométrico ou ligeiramente alométrico positivo, sinal de que os peixes começaram a engordar mais do que crescer. Finalmente, pode ser realçado que a maior variação do coeficiente de alometria correspondeu às trutas de cativeiro. Relativamente ao coeficiente de condição K, não foram observadas diferenças significativas quando comparada a condição das trutas selvagem antes e depois das experiências. No entanto, para as trutas de cativeiro observaram-se diferenças altamente significativas na sua condição.
- Conservation status of the freshwater pearl mussel Margaritifera margaritifera in PortugalPublication . Sousa, Ronaldo; Amorim, Ângela; Froufe, Elsa; Varandas, Simone; Teixeira, Amílcar; Lopes-Lima, ManuelBased on new information, the current conservation status of the freshwater pearl mussel Margaritifera margaritifera (Linnaeus, 1758) in Portugal is revised. Between 2010 and 2013 surveys were conducted in eight different rivers to assess distribution, abundance, size-frequency and preferential habitat of this species. Rivers Neiva, Cávado and Terva presented very low abundances (in the Cávado no specimens were found) and showed acute signs of ageing, calling into question the future survival of these populations. Although abundances were low in Rivers Beça, Paiva and Mente, juveniles were present and populations may improve their conservation status in the future, if appropriate management measures are applied. Rivers Rabaçal and Tuela presented the highest abundances of adults and juveniles and these two rivers have the highest potential for the conservation of freshwater pearl mussels in Portugal. However, these two populations have suffered severe declines in several stretches due to the construction of dams in recent years. Given that the Portuguese pearl mussel populations are at the southern range of the species distribution, their conservation should be a priority. This current description of the conservation status of M. margaritifera in Portugal can be used as a reference, and guide future research and management initiatives to better conserve this species.
- The male and female complete mitochondrial genomes of the threatened freshwater pearl mussel Margaritifera margaritifera (Linnaeus, 1758) (Bivalvia: Margaritiferidae)Publication . Gomes-dos-Santos, André; Froufe, Elsa; Amaro, Rafaela; Ondina, Paz; Breton, Sophie; Guerra, Davide; Aldridge, David C.; Bolotov, Ivan N.; Vikhrev, Ilya V.; Gan, Han Ming; Gonçalves, Duarte V.; Bogan, Arthur E.; Sousa, Ronaldo; Stewart, Donald; Teixeira, Amílcar; Varandas, Simone; Zanatta, David; Lopes-Lima, ManuelThe complete mitogenomes of one (M-)ale (North America), one Hermaphroditic (Europe), and two (F-)emale (North America and Europe) individuals of the freshwater pearl mussel Margaritifera margaritifera were sequenced. The M-type and F-type (Female and Hermaphroditic) mitogenomes have 17,421 and 16,122 nucleotides, respectively. All with the same content: 13 protein-coding genes, 22 transfer RNA, two ribosomal RNA genes, and one sex-related ORF. The M-type is highly divergent (37.6% uncorrected p-distance) from the F-type mitogenomes. North American and European F-type mitogenomes exhibit low genetic divergence (68 nt substitutions), and the Female and Hermaphroditic European mitogenomes are almost identical, and matching sex-related ORFs.